Process of making a dust-free alkaline detergent product



March 8, 1949. T. E. CORRIGAN 2,463,680

PROCESS OF MAKING A DUST-FREE ALKALINE DETERGENT PRODUCT Filed March 31, 1945 2 Sheets-Sheet l compouzn'r A (e CAUSTIC SODA) compouam' a e. .-sooA AsH) SCREEN FINISHED PRODUCT FINES FIG. I

INVENTOR. 7770mm? 6. (a/r1740 BY WM a? homey Mar h 8. 1949. T. E. CORRIGAN 2,463,630

PROCESS OF MAKING A DUST-FREE ALKALINE DETERGENT PRODUCT Filed March 51, 1945 2 Sheets- Sheet 2 I FIG. 2 FIG. 3

INVENTOR Thomas 5 Corn m ZdZlm K AT TOR EY Patented Mar... 8, 1949 PROCESS OF MAKING A DUST-FREE ALKALINE DETERGENT PRODUCT Thomul.

Corrlgan, to Wyandotte Chemi dotte, Mich. a corporation of Michigan Wyandotte, Mich, alsignor cals Corporation,

Wynn- Appllcafloli March 31, 1945, Serial No. 585,918 1 Chim. (Cl. 252-156) Various alkali compounds such as caustic soda (sodium hydroxide), soda ash (sodium carbonate), sodium phosphates and silicates, haveheretofore been mixed together in order to produce formulations or compositions having considerable usage in the industrial cleaning and detergent arts. One of the major difilculties encountered inthemakingupofsuchmixtureshasbeenthat the separate particles oi the individual compounds forming the ingredients of the mixture tend to segregate or to acquire non-uniform distribution-throughout the bulk of the mixtures, particularly on handling. transportation and storage. This difilculty becomes quite pronounced in the case where a relatively light powdery ingredient such as "1i8ht grade soda ash is admixed with a relatively heavier ingredientsuchas causticsodalnanyoneofitssolid forms, 1. e., granular, powder, fiake, etc. In addi-- tion, such mixtures are quite dusty, and during handling and transportation, the movement of the heavier particles of one ingredient or compound within the bulk mixture tends to have a milling or grinding efifect creating still more dust or powder content therein. This self-milling" effect ispresent even during the mixing of the alkali compound ingredients, and prior to pack agingorshipninansothatasaresultalarge amount of fines" are formed in the manufacturing process, and these fines represent a certain amount of loss and economic burden in that they must either be discarded or reworked.

My present invention, which overcomes the foregoing difiiculties, consists of rolling or compressing of the alkali compound mixtures into a sheet-like form so that the individual particles of the alkali mixture product are in the form of individual sheet particles or flakes, each one of which is itself a mixture of the alkali compound ingredients. The method of making the product of my invention involves the breaking-up of the original compressed or rolled sheet into smaller size sheets or fiakes, so that the entire mixture may be screened or classified. This permits a flexible and convenient determination of desired particle size in the final product without being dependent on the particle size of the originally admixed ingredients. The product of my invention, therefore, the advantages of being non-segregating. dust-free and of uniform particle size.

To the accomplishment of these and additional objectives and to enable any person skilled in the art readily to understand and practice the invention, the following full and concise description 2 a and annexed drawing setiorth the best mode in which I have contemplated applying the principle thereof. v

In said annexed drawing Fig. 1 is a flow sheet illustrating the process of my invention; and

Figs. 2 to 5, inc., are photomicrographs of sheet-like or fiake particles of various alkali compound mixtures made according to such process and illustrating the form of the: product of my invention. I r

When alkali compounds, such as those which are customarily formulated into alkali detergent mixtures, are simply stirred or admixed together, the individual particles of the chemical compounds forming the constituents thereof can be visually identified and separated one from the other. In fact, picking apart of the individual granules of the caustic soda and soda ash, for example, has constituted one simple method by those skilled in the art for eiiecting a rough analysis of an alkali detergent mixture. However, when these simple alkali compound mixtures are subjected to pressure, such as being rolled out into a thin sheet, the individual particles become bound together into thin fiakes, each one of which is indistinguishable from the other and is of itself an admixture of the original, separate ingredients.

I have discovered that alkali compound mixtures can be satisfactorily compressed or rolled into sheet-like form in which the original particles become bonded together to produce a new form of product of fiaked particles each of which constitutes a mixture of the original alkali compound ingredients. This applies particularly to mixtures containing compounds such as sodium hydroxide or sodium carbonate and in which there are two or more alkali compounds present such as those selected from the group of sodium orthosilicate, sodium metasilicate and sodium subsilicates (i. e., those in which the ratio of NaaO to S10: in the formula XNaa.YSiO: is

greater than 2 to 1), sodium hexametaphosphate, I

trisodium phosphate, tetrasodium pyrophosphate, and zincated caustic soda.

Fig. 1 illustrates one preferred method for practicing the process of my invention. The ingredients referred to therein, by way of exemplary illustration, are caustic soda and soda ash which are first simply introduced and stirred together in the mixer. The simple mixture is passed into the compression rolls where it is rolled out into thin sheets or flakes having a thickness in the range of .01 to 0.25 inch. Attempts to roll the mixtures into sheets or flakes of greater or lesser thickness than this range do not generally prove successful and hence I have determined that this optimum range of thickness is the best mode for practicing my invention. The sheets or relatively large flakes issuing from the compression rolls are next introduced to the grinding mill where they are subjected to a breaking-up action. Corrugated rolls or a hammer mill constitute satisfactory apparatus for this stage of the process. After the grinding or breaking-up of the large flakes into relatively smaller flakes, the resultant product is then passed over the screen whereby the fines are removed and the finished product is ready for and use. The fines are preferably returned to the compression rolls where they are added to the original mixture and very simply and conveniently compressed together with such mixture as it passes through the rolls. Alternatively, the flnes may be returned to the initial step of the process, namely, to the mixer.

The amount of flnes in the flnal product of my process is considerably reduced as compared to alkali compound mixing practices which have previously been employed. After considerable operation on a commercial scale, it has been determined that practically 100% of the components or ingredients originally introduced to the process goes directly to the formation of the flnished product. Thus, the problems heretofore encountered of accommodation and disposal of a relatively large amount of flnes, are substantially eliminated in my process.

Preferably my process is conducted at room or normal temperature, since when operating upon the alkali compound ingredients indicated above, the interbonding action between the separate particles or granules of such ingredients is sufliciently satisfactory to produce a good, hard flake.

' The possible hazard incident to the application of an amount of heat which would produce a semifluid. gummy mass or would incite a reaction between the individual ingredients, is likewise eliminated.

The following examples will better serve to illustrate the principle of my invention to those skilled in the art and more readily to enable the understanding and practice of same. These examples are given by way of illustration and not in limitation, the scope and particular deflnition of my invention being set forth in the appended Example 1 Equal parts by weight of crystal caustic soda (sodium'hydroxide) of 10 to.20 mesh particle size and light soda ash (sodium carbonate) were mixed together. The light soda ash had a'screen analysis as follows:

Percent by weight 100 mesh or larger 24 200 mesh or larger '73 2'10 mesh or larger 83 This mixture was fed between two 8 inch diameter rolls turning at 27 R. P. M. Prior to feeding in of this mixture, the rolls were set together with their surfaces in contact. As the mixture, passed between the rolls, they were slightly forced apart against resistance pressure.

4 mill where they were broken up into individual flakes of 16 to 20 mesh particle size, having a bulk density of .938 and producing a dust-free product of uniform appearance and uniform chemical constituency throughout its mass.

Example 2 A technically dry mixture of sodium metasilicate and sodium orthosilicate flnes was passed through the same 8 inch diameter rolls. The resultant flake from the rolls was .04 inch thick and is explifled in Fig. 3 which is a photomicrograph taken at 2 diameters under reflected light.

Example 3 A mixture of caustic soda, sodium metasilicate fines, and trisodium phosphate with a small amount of resin added, was passed through the compression rolls, resulting in a flake of .1 inch in thickness and having the appearance as shown in Fig. 4 which is also a photomicrograph taken at 2 diameters under reflected light. As will be noted from Fig. 4, the individual flakes show some darker areas which represent the resin constituent, and thus excellentlyserve to illustrate the manner in which the individual ingredients are distributed throughout the individual flaked particles.

. Example 4 A mixture comprising sodium metasilicate flnes, crystal caustic soda and tetrasodium pyrophosphate was passed through the rolls and the resultant flake was approximately .03 inch thick. It was then broken up into smaller flakes and passed through a inch mesh screen. The flnal product therefrom was as shown in the photomicrograph of Fig. 5 (2 diameters under reflectedlight) Example 5 A mixture of caustic soda, sodium hexametaphosphate and zincated causticv soda (ZnO in fused NaOH) was passed through the flaking rolls.

The resultant flake was approximately .1 inch in thickness, which-was subsequently passed over a 20 mesh screen. Oi. a total run of 2394 lbs. of the mixture passed through the compression rolls and the grinding mill, 2205 lbs. of 20 mesh or larger flakes were produced as the final product, leaving only 189 lbs. less than 20 mesh fines. These flnes are then available for use in the next batch. This represents only 7.9% production of flnes even though the material has been subjected to a grinding operation, and the starting materials themtogether substantially equal parts by weight of dry solid sodium hydroxide of 10 to 20 mesh particle size and dry solid sodium carbonate the majority of which has a particle size not larger than mesh, rolling-such mixture under pressure into a sheet-like flake having a thickness of not over 0.1 inch, and then breaking such flake into smaller flake particles, the majority of the latter having a particle size of no smaller than 20 mesh.

'THOMAS E. COBRIGAN. (References on following page) Number Name Date REFERENCES CITED 2,041,448 Zinn May 19, 1936 The following references are of record in the 2,282,013 Baker May 5, 1942 file of this patent: 2,303,397 Schwartz Dec. 1, 1942 UNITED STATES PATENTS OTHER REFERENCES Number Name Date Chemical Formulary, Bennett, vol. 6 (1943), 195,267 Elliott et a1 Sept. 18, 1877 pages 481 and 482, Bureau of Standards Circular, 1,715,999 Flammer et a1 June 4, 1929 C424 (1939), page 19.

2,035,652 Hall Mar. 31, 1936 lo 

